1. Field of the Invention
This invention relates to an electrical plug locking device. More particularly, it relates to a device for prohibiting unauthorized use of electrical appliances.
2. Description of Prior Art
Electrical plug locking devices of various designs are known in the prior art. U.S. Pat. Nos. 2,733,416, 4,566,297, 5,171,155, and 5,169,326 disclose electrical plug locking devices having a housing with an opening to receive at least one prong of an electrical plug. Each one of these U.S. Patents contains a locking member engaging with at least one inserted prong aperture of an electrical plug. A key or combination lock prohibits the plug from being removed without the proper key or combination. A spring engages or releases the locking member from the inserted prong.
U.S. Pat. No. 4,957,446 discloses a lockout device for electrically operated equipment and devices. The lockout device has a housing for receiving at least two prongs of an electrical plug. An externally accessed passageway in the housing axially aligns with holes in the electrical plug prongs. A latching means extends through the passageway and the holes of the prongs to prohibit the plug from being removed from the lockout device.
Although the prior art discloses electrical plug locking devices that successfully prohibit the unauthorized use of an electrical device, such devices have inherent disadvantages. One such disadvantage is the incorporation of a spring mechanism to facilitate movement of the locking means. Springs wear out over time thereby limiting the useful life of a device containing such an element. Other prior art devices contain complex mechanical structures, increasing manufacturing cost and consumer cost. In U.S. Pat. No. 4,957,446 the latching means is preferably comprised of a flexible strap. The strap is externally accessed and could be easily cut.
There is a need for an improved electrical plug locking device having an internal locking mechanism that is simple in design, thereby keeping manufacture and consumer cost low. The device needs to be durable and resistant to breakage to deter tampering. Finally, the electrical plug locking device needs to be devoid of a locking spring mechanism, but still prevent disengagement of the electrical plug prongs from the locking device.